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Inaba, Yoshitomo; Ishihara, Masahiro; Niimi, Motoji; Kawamura, Hiroshi
Journal of Nuclear Materials, 417(1-3), p.1348 - 1351, 2011/10
Times Cited Count：4 Percentile：31.39(Materials Science, Multidisciplinary)The Japan Materials Testing Reactor (JMTR) is a testing reactor with first criticality in March 1968. JMTR has been utilized for various neutron irradiation tests on nuclear fuels and materials, as well as for radioisotope production. The operation of JMTR was stopped in August 2006 for the refurbishment and the improvement. The renewed JMTR will be operated from FY 2011. Aiming at the restart of the new JMTR, the renewal of the aging reactor components, the preparation of the new irradiation facilities, and the development of the irradiation technologies have been carried out in JMTR. The irradiation facilities and technologies can also contribute to the development of fusion reactor materials. In this paper, the present status of the refurbishment and the irradiation technologies focused on the instrumentation in JMTR are described.
Tanaka, Kosuke; Kawamata, Kazuo; Yoshimochi, Hiroshi; Sozawa, Shizuo; Onose, Shoji; Niimi, Motoji; Asaka, Takeo
Proceedings of 1st Asian Symposium on Material Testing Reactors (ASMTR 2011), p.71 - 76, 2011/02
Post irradiation examination (PIE) facilities have been operated for about 40 years at the Oarai Research and Development Center of the Japan Atomic Energy Agency to investigate the performance and soundness of irradiated fuels and materials. The JMTR Hot Laboratory (JMTR-HL) was founded in 1971 mainly to examine the objects irradiated in the Japan Material Testing Reactor (JMTR). The Alpha-Gamma Facility (AGF) was constructed as the first laboratory to perform PIE of plutonium-bearing fuels for Japanese fast reactor development programs. This facility started hot operation in 1971 and has performed physical, metallurgical, and chemical examinations of irradiated fuels including uranium plutonium mixed oxide fuels. A renewal plan for the JMTR-HL and AGF is now in progress, associated with re-operation of the JMTR.
Kaminaga, Masanori; Niimi, Motoji; Hori, Naohiko; Takahashi, Kunihiro; Kanno, Masaru; Nakagawa, Tetsuya; Nagao, Yoshiharu; Ishihara, Masahiro; Kawamura, Hiroshi
JAEA-Review 2009-056, 20 Pages, 2010/02
JAEA-Review-2009-056.pdf:8.35MB
The JMTR is a light water moderated and cooled, beryllium reflected tank- type reactor using LUE silicide plate-type fuels. Its thermal power is 50 MW, maximum thermal and fast neutron flux is 4 
10
m
s
. First criticality was achieved in March 1968, and its operation was stopped from August, 2006 for the refurbishment. The refurbishment is scheduled from the beginning of FY2007 to the end of FY2010. The renewed and upgraded JMTR will be re-started from FY2011. An investigation on aged components (aged-investigation) was carried out for concrete structures of the JMTR reactor building, exhaust stack, etc., and for tanks in the primary cooling system, heat exchangers, pipes in the secondary cooling system, cooling tower, emergency generators and so on, in order to identify their integrity. The aged-investigation was carried out at the beginning of FY2007. As a result, some components were decided to replace from viewpoints of future maintenance and improvement of reliability, and some components or structures were decided to repair. A visual inspection of inner side of the pressure vessel was carried out using an underwater camera in FY2008, and no serious damage was observed. Up to now, refurbishment works are in progress according to the planned schedule. In this paper, current status of JMTR refurbishment project is presented.
Ishihara, Masahiro; Kawamura, Hiroshi; Niimi, Motoji; Kaminaga, Masanori; Hori, Naohiko; Nagao, Yoshiharu
Proceedings of 12th International Group on Research Reactors (12th IGORR) (USB Flash Drive), 10 Pages, 2009/10
The JMTR is a light water cooling tank typed reactor with first criticality in March 1968. The JMTR has been applied to fuel/material irradiation tests for LWRs, HTGR, fusion reactor and RI production. However, the JMTR operation was once stopped at August 2006, and the refurbishment works are now conducting. The reactor facilities will be renewed taking four years from the beginning of FY 2007, and necessary examination and works are carrying out on schedule. The renewed JMTR will be started from FY 2011, and be operated for a period of about 20 years until around FY 2030. The usability improvement of the JMTR, e.g. higher reactor availability-factor, shortening turnaround time to get irradiation results, attractive irradiation cost, business confidence, is also discussing with users as the preparations for re-operation. In the paper, status of the refurbishment of reactor facilities are introduced, moreover the future program using the JMTR will be prescribed.
Takemoto, Noriyuki; Nagao, Yoshiharu; Ishihara, Masahiro; Niimi, Motoji; Kawamura, Hiroshi
UTNL-R-0471, p.5_1_1 - 5_1_8, 2009/03
no abstracts in English
Kawamata, Kazuo; Nakagawa, Tetsuya; Omi, Masao; Hayashi, Koji; Shibata, Akira; Saito, Junichi; Niimi, Motoji
JAEA-Conf 2008-011, p.78 - 86, 2009/01
The JMTR-HL was founded to examine the objects mainly irradiated in the JMTR in 1971. The JMTR-HL has an advantage that the hot cell is connected with the reactor vessel of the JMTR by a canal. Hence it is easy to transport irradiated radioactive capsules and specimens through the canal. Since 1971, about 2,400 irradiated capsules have been treated in the JMTR-HL and various PIEs have been widely performed there. In recent years, several new techniques, e.g., an in-cell IASCC test, a scanning-electron microscope (SEM) / electron-back scattering-diffraction pattern (EBSD) observation, were added to the conventional PIEs. In addition, the JMTR-HL had contributed to realize an in-pile IASCC test program at the JMTR through the development of a TIG welding technique by remote-handling with manipulators in the hot cell for re-assembling of capsules. A modification of the facility to treat high burn-up fuels, up to about 100 GWD/t, is planned at the JMTR-HL now.
Takemoto, Noriyuki; Hanawa, Yoshio; Gorai, Shigeru; Fukasaku, Akitomi; Miyazawa, Masataka; Niimi, Motoji
JAEA-Conf 2008-010, p.97 - 105, 2008/12
Operation of the Japan Materials Testing Reactor (JMTR), a light-water-cooling tank-type reactor with a 50 MW thermal power, was stopped in August 2006, and now its refurbishment is on going. The reactor facilities are to be refurbished during four years from the beginning of FY 2007, and the renewed JMTR will be operated from FY 2011 until around FY 2030. As for the decision of the refurbishment, reactor facilities to be renewed and to be continuously used were selected from a viewpoint of ensuring safety, improvement of availability-factor, etc. The selected renewal reactor facilities were the reactor instrument and control system, cooling system, radioactive waste facility, power supply system, boiler, etc. Presented are the basic idea on selection of the renewal facilities, outline of these facilities and schedule of refurbishment work.
Nagao, Yoshiharu; Sato, Masashi; Niimi, Motoji
JAEA-Technology 2007-051, 73 Pages, 2007/09
JAEA-Technology-2007-051.pdf:6.1MB
An evaluation procedure using Monte Carlo method has been introduced to evaluate 
dose in neutron- mixing field of nuclear reactor. Benchmark calculations of the heating rate experiments in JMTRC and the nuclear heating rate measurements by the nuclear heating rate measurement capsule in JMTR were conducted by the procedure. As the results, it was confirmed that the procedure was applicable to evaluate /nuclear heating rate of JMTR. The nuclear heating distribution of JMTR core was analyzed, and the nuclear heating data maps were prepared. The values of the data maps were comparison with the results of irradiation tests by the nuclear heating rate measurement capsule. As the results, the values of the data map were within -27 to +35 % in comparison with the irradiation tests. The data maps are therefore utilizable for thermal design of irradiation capsule with more accurate temperature control, after refurbishment of the JMTR.
Ishii, Toshimitsu; Ooka, Norikazu; Hoshiya, Taiji; Kobayashi, Hideo*; Saito, Junichi; Niimi, Motoji; Tsuji, Hirokazu
Journal of Nuclear Materials, 307-311(Part.1), p.240 - 244, 2002/12
Times Cited Count：3 Percentile：22.77(Materials Science, Multidisciplinary)no abstracts in English
Nagao, Yoshiharu; Ishii, Tadahiko; Niimi, Motoji; Fujiki, Kazuo; Takahashi, Hidetake
JAERI-Review 2002-031, 119 Pages, 2002/11
JAERI-Review-2002-031.pdf:5.64MB
The published reports on the research and development activities using the JMTR since 1971 to date have been surveyed by the search of literature database and questionnaire survey. This report compiles the title lists and abstracts of reports published by JAERI and survey the trend of the research and development in JAERI using JMTR.
Nagao, Yoshiharu; Itabashi, Yukio; Komori, Yoshihiro; Niimi, Motoji; Fujiki, Kazuo
KAERI/GP-195/2002, p.49 - 55, 2002/00
An improved analysis procedure has been introduced to evaluate irradiation field at each specimen in the irradiation capsule by using the MCNP code, which is able to model the complicated structure of the capsule directly. As the verification results, it was confirmed that the calculated fast and thermal neutron flux/fluence were agreed with measured ones within 
10% and 30%, respectively, for the irradiation tests in the JMTR. Concerning gamma dose/spectrum, it was confirmed that the calculated temperature was evaluated within -3
+14% using gamma heating obtained by MCNP calculations. The evaluations of neutron flux/fluence and specimens temperature with high accuracy are therefore possible in the irradiation test of the JMTR.
Ishii, Toshimitsu; Ooka, Norikazu; Niimi, Motoji; Kobayashi, Hideo*
Kinzoku, 71(8), p.20 - 24, 2001/08
no abstracts in English
; Endo, Yasuichi; Yamaura, Takayuki; Matsui, Yoshinori; Niimi, Motoji; Hoshiya, Taiji; Kobiyama, M.*; Motohashi, Yoshinobu*
JAERI-Conf 99-006, p.343 - 348, 1999/08
no abstracts in English
Niimi, Motoji; Matsui, Yoshinori; Jitsukawa, Shiro; Hoshiya, Taiji; Tsukada, Takashi; Omi, Masao; Mimura, Hideaki; Ooka, Norikazu;
Journal of Nuclear Materials, 271-272, p.92 - 96, 1999/00
Times Cited Count：5 Percentile：40.11(Materials Science, Multidisciplinary)no abstracts in English
; Endo, Yasuichi; Yamaura, Takayuki; Hoshiya, Taiji; Niimi, Motoji; Saito, Junichi; ; Ooka, Norikazu; Kobiyama, M.*
Journal of Nuclear Materials, 258-263, p.2041 - 2045, 1998/00
Times Cited Count：6 Percentile：48.67(Materials Science, Multidisciplinary)no abstracts in English
Matsui, Yoshinori; Niimi, Motoji; Hoshiya, Taiji; Tsukada, Takashi; Tsuji, Hirokazu
Journal of Nuclear Materials, 258-263, p.378 - 382, 1998/00
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)no abstracts in English
; Endo, Yasuichi; Yamaura, Takayuki; Niimi, Motoji; Hoshiya, Taiji; Saito, Junichi; ; Ooka, Norikazu;
JAERI-Research 97-028, 46 Pages, 1997/03
JAERI-Research-97-028.pdf:2.49MB
no abstracts in English
Suzuki, Motoe; Tsukada, Takashi; Matsui, Yoshinori; Niimi, Motoji; Nakajima, Hajime
Proc. of 8th Int. Symp. on Environ. Degradation of Materials in Nuclear Power Systems - Water Reactors, 2, p.1013 - 1018, 1997/00
no abstracts in English
Arai, Yasuo; Iwai, Takashi; ; Okamoto, Yoshihiro; Nakajima, Kunihisa; Niimi, Motoji; ; Yamahara, Takeshi;
JAERI-Research 95-008, 92 Pages, 1995/02
JAERI-Research-95-008.pdf:5.04MB
no abstracts in English
Harayama, Yasuo; Hoshiya, Taiji; ; Niimi, Motoji; Kobayashi, Toshiki*
Journal of Nuclear Science and Technology, 30(4), p.291 - 301, 1993/04
Times Cited Count：4 Percentile：44.62(Nuclear Science & Technology)no abstracts in English
